This invention relates to a heat-shielding structure placed on a surface of an exhaust means or system of an automotive vehicle.
In general, a heat-shielding structure is provided in a portion of an exhaust means or system which is positioned between an exhaust manifold and the rear end of the vehicle. For example, such a heat-shielding structure is placed on a lower surface of a muffler or catalytic action device, or on an upper or lower surface of a front tube so as to shield radiant heat.
FIG. 4 shows a prior art heat-shielding structure disclosed in "skyline service report 386" issued in July 1979 by Nissan Motor Company. This prior art heat-shielding structure is composed of a steel plate pressed in a shape corresponding to a lower surface of a muffler. It is fixed at its edge portion to the muffler by means of a bolt.
In such a conventional heat-shielding structure, however, membrane vibration phenomenon may easily occur due to its structural defect. Because engine vibration is always transmitted to the exhaust means or system, the heat-shielding plate is easily excitedly vibrated so that big noise is produced from the surface of the heat-shielding structure.